It is the grand final. The two top designers have to complete three rooms each in converted apartments in an 18th-century mock castle in Broadstairs. The designers are tackling a kitchen for the first time ever and our designers soon find out that working in older properties is certainly not without its challenges. Judging this epic battle are Daniel Hopwood and Kelly Hoppen, helped and joined by former judge and interior stylist Sophie Robinson. Only one designer can walk away as winner of The Great Interior Design Challenge. Meanwhile, architectural historian Tom Dyckhoff explores the castle and explains the significance of such a beautiful building in British history.